Method of recovering bromine



Patented Nov. 6, 1%23.

UNHTEE STATES tenses rarest carter.

COULTER W. JONES, OF MIDLAND, MICHIGAN, ASSIGNOE TO THE DOW CHEIHGAE, GOMEANY, F MIDLAND, MICHIGAN, A UOEPOMTIQH (OF MICHIGAN.

METHOD OI? RECOVEBING JBEOIZIIME.

I30 Drawing;

To all whom it my concern:

Be it known that I, GouLrrER W. Jones, a citizen of the United States, and a resident of Midland, county of Midland, and State of Michigan, have invented a new and-use ful Improvement in Methods of Recovering Bromine, of which the following is a specification, the principle of the invention being herein explalned and the best mode in which I have contemplated applying that principle, so as to distinguish it from other 1nventions.

In the so-called Dow process of extract ing' bromine from natural brines, as de- 1 scribed in United States Letters Patent Re. No. 11,232, issued to H. H. Dow, April 12, 1892, the brine is treated to set the bromlne free from its chemical combination, whereupon such bromine goes into solution in the 2 brine and is then freed therefrom by an air blast, being finally absorbed with a suitable absorbing reagent from the air used 1n the blowing out step. The treatment of the brine to free the bromine is generally re- 2 ferred to as an oxidization step, and as stated in the patent in question, may be accomplished electrolytically or 'by the agency of chlorine gas or by ot or means; Whatever the agency thus employed, I have found It desirable that the oxidation be carried to a stage where a permanent excess of chlorine is present in the brine; i. e. where the freeing of the bromine is electrolytically accom-. plished, the electrolysis is carried to a stage beyond that necessary to simply free the bromine, so that a chlorine residuum is left; while if chlorine isemployed directly as the agent to free the bromine, more is intro duced into the brine than would be required to simply free the bromine.

In any event, there will be presented the problem of eliminating the free chlorine which thus remains in the brine after the oxidation step, and while it has heretofore been undertaken to remove traces of chlorine from the bromine-laden air after the socalled blowing out step by employing suitable purification means, I have found it ontirel feasible and much more satisfactory to e lminate such excess chlorine before the bromine is recovered from the brine' To the accomplishment of the stated object, the invention then consists of the ste s hereinafter fully described and particular y pointed out in the claims, the following do Application filed may 7, 19%. serial No. $79,489.

scription setting forth but one of several ways 1n which the rinciple of the invent1on may be utilized? It is of course known that chlorine will dlrectl react with water to a degree, presumab y formin in the first instance hypochlorous acid w ich then breaks down or gives ofi' oxygen with the resulting formation of hydrochloric and possibly some" chloric aci It is also of course known that this reaction between chlorine and water may be hastened by exposure to sunli ht or actlnic rays from any source. What have discovered is that this characteristic of chlorine to unite directly with water may be 7 utilized in a selective fashion so as to cause the elimination of such chlorine in a solution in which bromine is alsopresent in advance of any appreciable reaction between the bromine and the water.

In order to practically apply this discovery to the process in hand, after the oxidization step the brine containing an excess of chlorine as stated may be simply allowed to stand in a suitable tank or other container, a period of approximately six to seven hours being necessary under ordinary conditions and at room tem rature to cause the chlorine to substantially entirely disappear as such, if not too largely in excess at the start. However, to facilitate the reaction and avoid the necessit of large storage containers, by exposing t e oxidized brine either to sunlight or preferably owing to the uncertainty of the latter being available when desired, to actinic rays such as produced by a mercury vapor lamp, the reaction in uestlon will occur almost instantaneously. In act, it is necessary to carefully gauge the rate of flow. of the brine or in other words the length of time that it is exposed to the action of such light so as to avoid combination of the. free bromine.

After treatment in the manner described, the bromine remaining in solution therein is practically pure and upon its being recovered as by the familiar blowing out process or in any other way, it may be utilized directly in the manufacture of commercial bromides, or if recovered without 105 undue dilution with air, it may be liquefied and so utilized in this form.

My improved process is not necessaril limited to treatment of the so-called oxidized brine, i. e. brine in which the bromine 110 has been freed from its compounds along with a quantum of chlorine, butmay also be employed successfully in the removal of such excess of chlorine from the gaseous mixture that results from the blowing out step. Assuming, as will naturally be the case, that sufiicient moisture, i. e. water, is resent in this gaseous mixture, the result 0 exposure of the same to actimc rays of li ht will be to cause the preferential combination of such chlorine with the water leaving the free bromine in relatively pure state behind.

Other modes of applying the dprinciple of my invention may beem'ploye instead of the one explained, change'ibeing made as regards the method hereindisclosed, provided the step or steps stated by any of gtgllowing claims or the equivalent of such" stated step or steps be employed. l

I therefore particularly point out anddistinctly claim as my invention 1. In the extraction of bromine from bromide-containing brine, the steps which consist in treating such brine so as to leave free chlorine therein in excess of that required to free the bromine present, thereupon combinin such excess chlorine, and

then treating the brine to remove the free bromine, substantially as described.

consist in treating such brine so as to leave ifree chlorine therein in excess of that re- "quired to free. the bromine present, therebromide-containing brine, the steps which consist in treating such brine so as to leave free chlorine therein in excess of that required to free the bromine present, thereupon exposing such brine to actinic rays of light, Whereb such excess' 0t chlorine is combined wit the water oflltlie brine to form hypochlorous acid or derivatives, and then treating the brine to remove free bromine substantially as described 4. The method of purifying bromine, either in liquid solution or gaseous form, from an admixture of chlorine, which consists in exposing such mixture to actinic rays of light in the presence of water, whereby such chlorine preferentially combines with such water, substantially as deme, at Midland, Michigan, this I scribed Signed 113E1- day of ay,1920. 2. In the extractlon of bromine from fbromide-containing brine, the steps which I .COULTER w. JON-ES.- 

